Human Placental Sialidase: Partial Purification and Characterization

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Abstract
A sialidase [EC 3.2.1.18] has been partially purified from human placenta by means of procedures comprising Con A-Sepharose adsorption, ammonium sulfate precipitation, sucrose density gradient centrifugation, and high-pressure liquid chromatography on a Shim pack Diol 300 column. On high-pressure liquid chromatography, most of the β-galactosidase that comigrated with the sialidase on sucrose density gradient centrifugation was removed. The sialidase was purified 3, 600-fold from the preparation obtained by Con A-Sepharose adsorption. The enzyme liberated the sialic acid residues from (α2-3) and (α2-6) sialyllactose, colomic acid, fetuin, and transferrin, but not from bovine submaxillary mucin. The enzyme also hydrolyzed gangliosides G M3 , G D1a , and G D1b in the presence of sodium cholate as a detergent, but G M1 and G M2 were less susceptible to the enzyme. The optimum pHs for 4-methylumbelliferyl- N -acetylneuraminate, sialyllactose, fetuin, and G M3 lay between 4.0 and 5.0.

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